Study on Reduction of Quench Recovery Time by Inductive Energy Extraction

Superconducting coils can generate high magnetic fields and are used in many applications in medicine, industry and research. A superconducting coil stores enormous amounts of magnetic energy, often more than 1 MJ, and this energy is released when a quench occurs. Therefore, quench protection methods, which prevent energy localization, have been developed to protect the coil and peripheral mechanisms. However, shortening the inactive time of the coil must be considered. Even in undamaged coils, in cryogen-free magnets, the coil temperature rises owing to the energy released and requires more time to cool to the operable temperature. Quenching can occur during power outages, training processes, and safety tests in coil manufacturing. Longer recovery times require longer lead times in the coil manufacturing process and result in longer downtime in situ. Therefore, we consider a quench protection method that removes energy from the coil to shorten the recovery time and increases the availability. In this study, we report the results of our study on inductive energy extraction.